There are various types of picture and poster frames in use today. Some of these are shown, for example, in U.S. Pat. Nos. 3,310,901, 4,041,632 and 4,145,828. Some common poster frame devices known today are front-loading frame devices, such as shown in U.S. Pat. Nos. 3,310,901 and 4,145,828. These devices have worked very well and have been commercially successful.
Most poster frame devices are square or rectangular in shape with four frame sections joined together in the four corners with corner keys or similar devices. The ends of the frame sections are typically mitered at 45.degree. at the corners, or are cut at 90.degree. and abut separate corner members. Poster frames with mitered corners are shown, for example, in U.S. Pat. No. 4,519,152, while poster frames with separate corner members are shown, for example, in U.S. Pat. No. 5,086,736. The corner keys and separate corner members add additional expense and assembly time to the frame devices.
Front-loading poster frames typically have frame sections with a pair of spring-biased rotating members, such as a cover member and a base member hingedly attached together. Where the cover and base members are made from metal materials, it has been found necessary to utilize rail locks or equivalent mechanisms in order to prevent the cover members from sliding longitudinally relative to the base members. These mechanisms include, for example, small threaded cylinders, material staking or swaging, and other interlocking mechanical mechanisms. See, for example, U.S. Pat. Nos. 4,937,959 and 4,958,458. These mechanisms also add expense and complexity to the total cost and assembly of the poster frames.